The invention relates generally to manufacturing of semiconductor devices and more particularly to the control of ozonated deionized water supplied to semiconductor processing tools.
Use of ozonated deionized water in semiconductor manufacturing can provide relatively simple, safe processing steps, such as wafer surface cleaning, passivation, native oxide removal, and removal of photoresist.
Ozonated deionized water generators generally produced ozonated water through use of contactors that permit diffusion of ozone from a gas into deionized water. Membrane contactors use an ozone permeable membrane to provide physical separation between liquid and gas, while packed column contactors provide intimate mixing of liquid and gas, under pressure to enable higher ozone concentrations.
A semiconductor fabrication facility often has multiple tools that require ozonated water. Different tools can require different ozone concentrations and flow rates. The purchase, operation and maintenance of multiple ozonated water generators can increase manufacturing costs and line shut-downs.
It would be beneficial to have a less expensive, more reliable, more flexible and more rapidly responsive ozonated water source.
The present invention relates to an ozonated water control unit for use in an improved ozonated water supply system. The control unit can modify the flow rate and/or concentration of ozonated water received from an ozonated water generator, for subsequent delivery to a process tool. One or more control units can be used with a single generator to supply more than one tool with individualized ozonated water needs.
In various embodiments, the ozonated water supply system can simultaneously supply ozonated water of different ozone concentrations to different process tools, even if the system includes only one ozonated water generator. Use of one or more control units with as few as one ozonated water generator permits independent control of ozonated water supplied to two or more process tools.
Each control unit controls its output flow rate and/or concentration of ozonated water. Thus, the parameters of the supplied ozonated water can be tailored for each process tool. In one embodiment, the system can supply low ozone concentration ozonated deionized water, for example, for a cleaning process, and simultaneously supply higher ozone concentration ozonated deionized water, for example, for a stripping process.
Thus, in a first aspect, the invention features a method of supplying ozonated water to more than one process tool. Ozonated water of a first concentration received from an ozonated water generator and water received from a source are mixed to produce ozonated water of a second concentration. Ozonated water of the second concentration is supplied to a first process tool, and ozonated water from the ozonated water generator is supplied to a second process tool.
In a second aspect, the invention features another method of supplying ozonated water to more than one process tool. The method includes providing an ozonated water control unit. The ozonated water control unit includes an ozonated water input line for receiving ozonated water of a first concentration from an ozonated water generator and a water input line for receiving water from a source. The unit also includes an ozonated water output line in fluid communication with the ozonated water input line and the water input line. A valve controls a flow rate of water in the water input line to produce ozonated water of a second concentration in the output line, in cooperation with a flow rate of ozonated water in the ozonated water input line.
The method further includes supplying ozonated water of the second concentration from the output line to a first process tool and supplying ozonated water from the ozonated water generator to a second process tool.
In a third aspect, the invention features an ozonated water control unit. The control unit includes an ozonated water input line for receiving ozonated water from an ozonated water generator, a water input line for receiving water from a source and an ozonated water output line in fluid communication with the ozonated water input line and the water input line. The unit also includes a valve for controlling a flow rate of water in the water input line to produce ozonated water of a second concentration in the output line, in cooperation with a flow rate of ozonated water in the ozonated water input line.
The invention, in accordance with preferred and exemplary embodiments, together with further advantages thereof, is more particularly described in the following detailed description, taken in conjunction with the accompanying drawings.